1. Field of the Invention
The present invention relates to information processing methods and information processing apparatuses.
2. Description of the Related Art
FIG. 1 is a diagram showing a scheme of ordinary color matching based on ICC profiles defined by the International Color Consortium (ICC). A profile connection space (PCS) linking profiles is based on the XYZ values and Lab values of white light D50.
RGB data input under the white light D50 is converted into device-independent values in an XYZ color space on the basis of an input profile. The resulting color space includes out-of-gamut colors that cannot be represented by an output device. Thus, color-space compression is executed via the PCS on the input data having been converted into data represented in the device-independent color space so that all the colors can be represented within the color gamut of the output device. After the color-space compression, the input data represented in the device-independent color space is converted into RGB data or CMYK data represented in a color space that is dependent on the output device. In processing based on ICC profiles, the conversion from the input color space to the XYZ color space and the conversion from the XYZ color space to the output color space are executed using a matrix or a lookup table (LUT).
A problem of the ICC profiles is that the reference white point and environment illumination are fixed.
FIG. 2 is a diagram showing a scheme of color matching in which the problem of ICC profiles is taken into consideration. In the color matching, input data that is dependent on a color space of an input device is converted into data represented in a device-independent color space on the basis of an input viewing condition, and the data is converted (forward-converted) into data represented in a human color perception space. Then, color-space compression is executed in consideration of the color gamut of the input device and the color gamut of the output device, and the data obtained through the color-space compression is converted (inverse-converted) into data represented in a device-independent color space on the basis of an output viewing condition. Then, the data is converted into output data represented in a color space that is dependent on the output device.
Color conversion from an input device to an output device according to the related art has been described above. In some cases, color matching is executed for the purpose of outputting input data to two different output devices, i.e., for the purpose of simulating or previewing an output to one of the output devices (first output device) by the other output device (second output device). In such cases, it is expected that an expected output to the first output device is reproduced by the second output device. Particularly, when the first output device is a printer and the second output device is a monitor, an output by the printer can be previewed on the monitor before printing. It will be understood that a high demand exists for such techniques. This has hitherto been achieved through the following techniques.
FIG. 3 is a diagram showing a scheme of use of ICC profiles. First, input data is converted from RGB values to XYZ values on the basis of an input profile. The XYZ values are converted into CMYK values on the basis of a printer output profile having a compressed color space, thereby obtaining output data for a printer. Furthermore, the printer data is converted from CMYK values to XYZ values on the basis of a printer input profile. The XYZ values are converted into RGB values on the basis of a monitor output profile having a compressed color space, thereby obtaining output data for a monitor.
FIG. 4 is a diagram showing a scheme of the method according to the related art described above. Input data is converted into XYZ values on the basis of a viewing condition 1 of input, the XYZ values are converted into data represented in a human color perception space, and color-space compression is executed in consideration of the color gamuts of the input data and the printer. Then, the values obtained through the color-space compression are converted into XYZ values on the basis of a viewing condition 2 of the printer, and the XYZ values are converted into data represented in the human color perception space. Then, color-space compression is executed on the data represented in the human color perception space in consideration of the color gamuts of the printer and the monitor. Then, the values obtained through the color-space compression are converted into XYZ values on the basis of a viewing condition 3 of the monitor. Finally, the XYZ values are converted into RGB values that are dependent on the monitor.
When ICC profiles are used, the reference white point and environment illumination are fixed, so that the problem remains.
On the other hand, when the method according to the related art is used, although the problem can be solved, color conversion must be executed ten times. When an output of the printer is to be previewed on the monitor before printing, a fast processing speed is desired. Thus, an improvement is desired to reduce time needed for the large number of times of color conversion.
Furthermore, when color conversion is executed for the purpose of previewing, data is not necessarily output to the printer. When the result of previewing differs from the expectation of the user, the data is not output from the printer. The user modifies the input data, changes the printer profile, changes the mode of color-space compression from input data to printer data, or otherwise performs an adjustment. In this case, it is useless to generate printer data, which is not output from the printer.